1. Field of the Invention
This invention relates generally to fuel pumps for internal combustion engines and relates particularly to fuel injection pumps for injecting gasoline under high pressure into a diesel type internal combustion engine.
2. Description of the Prior Art
Heretofore fuel pumps of various kinds have been provided for pumping fuel from a fuel supply tank to an internal combustion engine and many of these pumps have included diaphragms which were connected to a finger or lever and engaged a rotating cam to create a differential in pressure on at least one side of the diaphragm. Normally fuel is introduced into gasoline type internal combustion engines at relatively low pressures or during the suction stroke of the pistons and therefore such fuel pumps could use diaphragms constructed of rubber, neoprene or other resilient material.
Some efforts have been made to provide injection pumps which utilized a non-compressible fluid such as oil or the like on one side of the diaphragm so that the power stroke of a cam operated piston applied pressure to the oil and caused the diaphragm to move. The return stroke of the pump caused a suction or subatmospheric pressure to be applied to the diaphragm and caused the diaphragm to move to the other side of the diaphragm cavity so that fuel flowed into the cavity from which such fuel was pumped on the next power stroke of the piston. Some examples of the prior art are the U.S. Pat. Nos. to Gambrell 2,138,849; Dodson 2,343,962; Mashinter 2,948,223; Dean et al. 2,960,936; and Cary 3,620,649.